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[2003:cb:c708:1500:d584:7ad8:d3f7:5539]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-432d55417f3sm21648285e9.34.2024.11.13.03.43.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Nov 2024 03:43:31 -0800 (PST) Message-ID: <6e9c649f-5fc9-4fcc-928c-c4f46a74ca66@redhat.com> Date: Wed, 13 Nov 2024 12:43:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/7] mm: introduce do_zap_pte_range() To: Qi Zheng Cc: jannh@google.com, hughd@google.com, willy@infradead.org, mgorman@suse.de, muchun.song@linux.dev, vbabka@kernel.org, akpm@linux-foundation.org, zokeefe@google.com, rientjes@google.com, peterx@redhat.com, catalin.marinas@arm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org References: <1639ac32194f2b2590852f410fd3ce3595eb730b.1730360798.git.zhengqi.arch@bytedance.com> <2fd11f54-8c0c-401d-8635-e54ebf7facc2@bytedance.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <2fd11f54-8c0c-401d-8635-e54ebf7facc2@bytedance.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 4HVQ4TgS1WMHij3IL-wUuGrsjcSKgzLK0vS4oAMPbUI_1731498212 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 7EFE116001D X-Rspamd-Server: rspam11 X-Stat-Signature: y4bcmuzsbbhgkr4pd9cjxzhab7zjqddz X-HE-Tag: 1731498186-45781 X-HE-Meta: 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 srm/QKSX 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 13.11.24 03:40, Qi Zheng wrote: > > > On 2024/11/13 01:00, David Hildenbrand wrote: >> On 31.10.24 09:13, Qi Zheng wrote: >>> This commit introduces do_zap_pte_range() to actually zap the PTEs, which >>> will help improve code readability and facilitate secondary checking of >>> the processed PTEs in the future. >>> >>> No functional change. >>> >>> Signed-off-by: Qi Zheng >>> --- >>>   mm/memory.c | 45 ++++++++++++++++++++++++++------------------- >>>   1 file changed, 26 insertions(+), 19 deletions(-) >>> >>> diff --git a/mm/memory.c b/mm/memory.c >>> index bd9ebe0f4471f..c1150e62dd073 100644 >>> --- a/mm/memory.c >>> +++ b/mm/memory.c >>> @@ -1657,6 +1657,27 @@ static inline int zap_nonpresent_ptes(struct >>> mmu_gather *tlb, >>>       return nr; >>>   } >>> +static inline int do_zap_pte_range(struct mmu_gather *tlb, >>> +                   struct vm_area_struct *vma, pte_t *pte, >>> +                   unsigned long addr, unsigned long end, >>> +                   struct zap_details *details, int *rss, >>> +                   bool *force_flush, bool *force_break) >>> +{ >>> +    pte_t ptent = ptep_get(pte); >>> +    int max_nr = (end - addr) / PAGE_SIZE; >>> + >>> +    if (pte_none(ptent)) >>> +        return 1; >> >> Maybe we should just skip all applicable pte_none() here directly. > > Do you mean we should keep pte_none() case in zap_pte_range()? Like > below: > No rather an addon patch that will simply skip over all consecutive pte_none, like: if (pte_none(ptent)) { int nr; for (nr = 1; nr < max_nr; nr++) { ptent = ptep_get(pte + nr); if (pte_none(ptent)) continue; } max_nr -= nr; if (!max_nr) return nr; addr += nr * PAGE_SIZE; pte += nr; } Assuming that it's likely more common to have larger pte_none() holes that single ones, optimizing out the need_resched()+force_break+incremental pte/addr increments etc. -- Cheers, David / dhildenb